Fermented Taiwanese Grain Produces a Peptide That Inhibits a Key Blood Pressure Enzyme Nearly as Well as Captopril | Research

The takeaway

A 9-amino-acid peptide (DK9) extracted from red yeast-fermented djulis grain inhibited ACE at levels approaching the prescription drug captopril, with stronger computed binding affinity.

40.71% vs. 43.33% ACE inhibition
The fermented djulis peptide DK9 achieved ACE inhibition nearly matching captopril, a widely prescribed blood pressure drug, in laboratory tests

What the researchers found

Researchers identified ACE-inhibitory peptides produced during fermentation of djulis (a Taiwanese grain) with Monascus purpureus (red yeast). The protein hydrolysates from fermented dehulled djulis achieved 40.71% ACE inhibition by day 8 — approaching the 43.33% inhibition achieved by captopril, a widely prescribed blood pressure drug.

Using computational screening and proteomics, they identified a 9-amino-acid peptide called DK9 (DAAGYVADK) as the lead candidate. Molecular docking showed DK9 binds ACE with a binding affinity of -9.174 kcal/mol, stronger than captopril's -5.77 kcal/mol. DK9 works as a competitive inhibitor, and computational safety profiling predicted low toxicity and favorable drug-like properties.

Why it matters

High blood pressure affects over a billion people worldwide, and ACE inhibitors are among the most commonly prescribed medications. Finding natural, food-derived ACE-inhibitory peptides could lead to functional foods or nutraceuticals that support blood pressure management with potentially fewer side effects than synthetic drugs. The discovery that fermented djulis produces a peptide nearly as effective as captopril in lab tests — with stronger binding affinity — makes it a noteworthy lead compound for further development.

The numbers in context

40.71% ACE inhibition (vs. 43.33% for captopril) · DK9 peptide: DAAGYVADK · binding affinity: -9.174 kcal/mol (captopril: -5.77) · 7 hydrogen bonds with ACE active site · day 8 fermentation peak · competitive inhibition mechanism

How the study worked

Djulis grain was fermented with Monascus purpureus, and protein hydrolysates were tested for ACE inhibition at various time points. The researchers used computational screening with the BIOPEP database and proteomics to identify candidate peptides. The lead peptide DK9 was evaluated through molecular docking simulation, enzyme kinetics analysis, and ADMET (absorption, distribution, metabolism, excretion, toxicity) computational profiling.

Who was studied

In vitro ACE inhibition assays and computational analysis

What this study cannot tell us

This is entirely an in vitro and computational study — no animal or human testing was performed. ACE inhibition measured in a test tube does not necessarily translate to blood pressure reduction in living organisms, as the peptide must survive digestion, be absorbed, and reach the target enzyme. The comparison to captopril is based on in vitro inhibition percentages, not clinical efficacy. The ADMET predictions are computational estimates, not experimentally verified pharmacokinetic data.

How to read the evidence

This study is graded as preliminary because it is based entirely on in vitro enzyme assays and computational modeling. No animal or human testing was conducted to verify that DK9 lowers blood pressure in a living organism.

When this study was published

Published in 2026, this is a brand-new study at the forefront of food-derived bioactive peptide research.

The bigger picture

Food-derived ACE-inhibitory peptides are a growing area of nutraceutical research. Peptides from milk, fish, soy, and grains have all shown ACE-inhibitory activity, but most are weaker than pharmaceutical ACE inhibitors. DK9's near-captopril performance in vitro is notable and adds djulis — an underutilized pseudocereal — to the map of functional food sources. If bioavailability can be confirmed in vivo, fermented djulis products could become part of dietary approaches to blood pressure management.

Questions still open

Can DK9 survive digestion and maintain its ACE-inhibitory activity when consumed orally as a food or supplement?
Would fermented djulis products produce meaningful blood pressure reductions in human clinical trials?
How does DK9's in vivo efficacy compare to other food-derived ACE-inhibitory peptides like those from milk casein?

Common questions

What is djulis and why is it interesting for peptide research?

Djulis (Chenopodium formosanum) is a grain-like plant native to Taiwan, sometimes called Taiwanese quinoa. When fermented with red yeast (Monascus purpureus), it produces protein fragments — peptides — that can block ACE, an enzyme involved in raising blood pressure. This makes fermented djulis a potential source of natural blood pressure-supporting compounds.

Does this mean fermented djulis can replace blood pressure medication?

No — this study was conducted entirely in laboratory tests and computer simulations. While the peptide DK9 showed impressive ACE inhibition in a test tube, there is no evidence yet that eating fermented djulis would meaningfully lower blood pressure in people. Clinical trials would be needed before any such claims could be made.

Read the original research

Proteomic profiling of Monascus-fermented djulis (Chenopodium formosanum) identifies ACE-inhibitory peptides through integrated in silico and in vitro approaches.

Food chemistry, 500, 147474

View on PubMed ↗Publisher’s paper ↗

Citation

Lu, Jheng-Jhe; Cheng, Kuan-Chen; Khumsupan, Darin; Hsieh, Chen-Che; Hsieh, Chang-Wei; Santoso, Shella Permatasari; Angkawijaya, Artik Elisa; Kuo, Hsing-Chun. (2026). Proteomic profiling of Monascus-fermented djulis (Chenopodium formosanum) identifies ACE-inhibitory peptides through integrated in silico and in vitro approaches.. Food chemistry, 500, 147474. https://doi.org/10.1016/j.foodchem.2025.147474